The present invention relates to a polishing apparatus for polishing end faces of optical fibers mounted on their ferrules, and more particularly, to a high production polishing apparatus for polishing end faces of optical fibers to give them high quality convex spherical surfaces.
A connection between optical fibers for optical communication is accomplished by using a disconnectable optical connector or, for a permanent connection, an optical splicer. If the end faces of optical fibers are polished to have convex spherical surfaces and thereafter connected to each other, the return loss due to a reflection at the connection point can be reduced. Such a return loss due to reflection especially affects high-speed mass communication and therefore it is desirable to perform the convex spherical polishing of the end faces of optical fibers for this type of communication.
Heretofore, the convex spherical polishing for the end faces of optical fibers mounted on their ferrules has been carried out by using a rotary polishing disk formed with a concave spherical surface. The end faces of optical fibers mounted on their ferrules are pressed against the concave spherical surface with polishing powder therebetween and then are moved so that they are given polished convex spherical surfaces.
This conventional polishing method has a problem in that the end face of a ferrule has a relatively small curvature of the order on several centimeters, and therefore the effective polishing area of the polishing disk is limited to a very small dimension. Therefore, it is difficult to increase the polishing efficiency with this type of polishing method. For example, it takes about 30 to 60 minutes for one polishing step even when the polishing process is proceeding properly.
The conventional polishing method has another problem in that harmful substances consisting of a mixture of polishing dust, polishing liquid and polishing powder exist on the polishing disk and are often forced into the polishing disk so that they become buried. It is difficult to remove or clean such harmful substances from the polishing disk in view of the structure of the conventional polishing apparatuses. While it is necessary that the polishing powder be distributed evenly and uniformly and the surface roughness of the polishing disk be kept within a predetermined value, the harmful substances which become trapped in the polishing disk affect the reproducibility of the polishing quality.
Accordingly, the polishing process often needs to be repeated until a satisfactory result is obtained, thereby lowering the productivity of the polishing process. The conventional polishing process also requires skilled people for carrying this process.
It is an object of the present invention to provide a polishing apparatus capable of easily polishing end faces of optical fibers to give them convex spherical surfaces such that this process has good reproducibility of the polishing quality and does not require skilled labor to carry out the process.